1. Field of the Invention
This invention relates to data compression.
2. Description of Related Art
Currently, it is well known to record, transfer, and/or store data, such as, for example, documents, files, folders, pictures, sounds, music, videos, or the like, in the form of individual data files. Additionally, it is well known that large scale archiving and retrieval of data files can require high-capacity storage devices and media. Furthermore, it is also known that the transfer and storage of large quantities of data is increasing.
Generally, there are two methods for increasing the efficiency and reducing the cost associated with manipulating data. The first method involves increasing the rate at which data is transferred. By increasing the data transfer rate, a user can, for example, download a particular data file more quickly. However, increasing the data transfer rate does not reduce the amount of space needed to store the data once it has been transferred, or downloaded.
The second method for increasing the efficiency and reducing the cost of manipulating data involves decreasing the size of the data file itself, also known as compressing the data file. By compressing a particular data file, both the time required to transfer the data file and the amount of space needed to store the data file is reduced.
Data file compression is typically accomplished by dividing a data file into equal length data segments called data packets. Each data packet is then compressed, using a predetermined data compression ratio. The compressed data packets are then stored and/or transferred as a new, smaller data file.
Various data compression techniques can be used to compress a particular data file. However, when data is compressed, the reproduction quality of the compressed data is reduced because data reproduction quality is inversely proportional to the data compression ratio. To illustrate, if a user saves a piece of music on his or her computer, using a high data compression ratio, the stored music file will take up less storage space on the user's computer than the music would if it had been saved using a low data compression ratio. However, when the user replays the stored piece of music, the music will not sound as clear as it would have if the music had been saved using a low data compression ratio.
Therefore, if a particular data compression technique uses a high data compression ratio, the size of the data file containing the compressed data will be smaller, but the data reproduction quality will be reduced. In contrast, if a low data compression technique is used to compress the data, the data reproduction quality will be higher, but the resulting data file may be extremely large.
As a result, when data is recorded, stored, and/or transferred, a choice must be made between increased data file size and increased data reproduction quality.
Typically, a moderate data compression ratio is selected. Using a moderate data compression ratio allows the overall size of the data file to be reduced enough to allow somewhat convenient data file manipulation while allowing the data reproduction quality to be high enough to provide the user with a tolerable level of data reproduction distortion. Once a data compression ratio is chosen, the data compression ratio is applied to all of the data packets in the data file.